Files
kobo-font-fix/kobofix.py

857 lines
32 KiB
Python
Executable File

#!/usr/bin/env python3
"""
Font processing utility for Kobo e-readers.
This script processes TrueType fonts to improve compatibility with
Kobo e-readers by:
- Adding a custom prefix to font names
- Updating the font name if necessary, including PS name
- Extracting GPOS kerning data and creating legacy 'kern' tables
- Validating and correcting PANOSE metadata
- Adjusting font metrics for better line spacing
- Updating font weight metadata (OS/2 usWeightClass and PostScript weight string)
Requirements:
- fontTools (pip install fonttools)
- font-line utility (https://github.com/source-foundry/font-line)
"""
import sys
import os
import subprocess
import argparse
import logging
from pathlib import Path
from collections import defaultdict
from dataclasses import dataclass
from typing import Dict, Tuple, Optional, List
from fontTools.ttLib import TTFont, newTable
from fontTools.ttLib.tables._k_e_r_n import KernTable_format_0
# Constants
DEFAULT_PREFIX = "KF"
DEFAULT_LINE_PERCENT = 20
DEFAULT_KOBO_KERN = True
VALID_SUFFIXES = ("-Regular", "-Bold", "-Italic", "-BoldItalic")
SUPPORTED_EXTENSIONS = (".ttf")
# Configure logging
logging.basicConfig(level=logging.INFO, format='%(message)s')
logger = logging.getLogger(__name__)
@dataclass
class FontMetadata:
"""A container for consistent font naming and metadata."""
family_name: str
style_name: str
full_name: str
ps_name: str
class FontProcessor:
"""Main font processing class."""
def __init__(self, prefix: str = DEFAULT_PREFIX, line_percent: int = DEFAULT_LINE_PERCENT, kobo_kern_fix: bool = DEFAULT_KOBO_KERN):
"""
Initialize the font processor.
Args:
prefix: Prefix to add to font names
line_percent: Percentage for baseline adjustment
kobo_kern_fix: Apply `kern` table fix for Kobo devices
"""
self.prefix = prefix
self.line_percent = line_percent
self.kobo_kern_fix = kobo_kern_fix
# ============================================================
# Metadata extraction
# ============================================================
def _get_font_metadata(self, font: TTFont, font_path: str, new_family_name: Optional[str]) -> Optional[FontMetadata]:
"""Extract or infer font metadata from the font and arguments, prioritizing filename suffix."""
if "name" not in font:
logger.warning(" No 'name' table found; cannot determine metadata.")
return None
name_table = font["name"]
# Determine family name
family_name = new_family_name if new_family_name else name_table.getBestFamilyName()
if not family_name:
logger.warning(" Could not determine font family name.")
return None
# Determine style name from filename suffix
base_filename = os.path.basename(font_path)
style_map = {
"BoldItalic": "Bold Italic",
"Bold": "Bold",
"Italic": "Italic",
"Regular": "Regular",
}
style_name = "Regular" # Default to regular if no suffix found
# Iterate through styles and check if filename contains the style string
for style_key, style_val in style_map.items():
if style_key.lower() in base_filename.lower():
style_name = style_val
break
# Construct the full name and PS name based on style name logic
full_name = f"{family_name}"
if style_name != "Regular":
full_name += f" {style_name}"
ps_name = f"{self.prefix}{family_name.replace(' ', '')}"
if style_name != "Regular":
ps_name += f"-{style_name.replace(' ', '')}"
logger.debug(f" Constructed metadata: family='{family_name}', style='{style_name}', full='{full_name}', ps='{ps_name}'")
return FontMetadata(
family_name=family_name,
style_name=style_name,
full_name=full_name,
ps_name=ps_name
)
# ============================================================
# Kerning extraction methods
# ============================================================
@staticmethod
def _pair_value_to_kern(value1, value2) -> int:
"""
Compute a legacy kerning value from GPOS PairValue records.
Args:
value1: First value record
value2: Second value record
Returns:
Integer kerning value (may be negative)
"""
kern_value = 0
# Prefer XAdvance adjustments
if value1 is not None:
kern_value += getattr(value1, "XAdvance", 0) or 0
if value2 is not None:
kern_value += getattr(value2, "XAdvance", 0) or 0
# Fall back to XPlacement if no XAdvance
if kern_value == 0:
if value1 is not None:
kern_value += getattr(value1, "XPlacement", 0) or 0
if value2 is not None:
kern_value += getattr(value2, "XPlacement", 0) or 0
return int(kern_value)
def _extract_format1_pairs(self, subtable) -> Dict[Tuple[str, str], int]:
"""Extract kerning pairs from PairPos Format 1 (per-glyph PairSets)."""
pairs = defaultdict(int)
coverage = getattr(subtable, "Coverage", None)
pair_sets = getattr(subtable, "PairSet", [])
if not coverage or not hasattr(coverage, "glyphs"):
return pairs
for idx, left_glyph in enumerate(coverage.glyphs):
if idx >= len(pair_sets):
break
for record in getattr(pair_sets[idx], "PairValueRecord", []):
right_glyph = record.SecondGlyph
kern_value = self._pair_value_to_kern(record.Value1, record.Value2)
if kern_value:
pairs[(left_glyph, right_glyph)] += kern_value
return pairs
def _extract_format2_pairs(self, subtable) -> Dict[Tuple[str, str], int]:
"""Extract kerning pairs from PairPos Format 2 (class-based)."""
pairs = defaultdict(int)
coverage = getattr(subtable, "Coverage", None)
class_def1 = getattr(subtable, "ClassDef1", None)
class_def2 = getattr(subtable, "ClassDef2", None)
class1_records = getattr(subtable, "Class1Record", [])
if not coverage or not hasattr(coverage, "glyphs"):
return pairs
# Build left-side glyph lists per class
class1_map = getattr(class_def1, "classDefs", {}) if class_def1 else {}
left_by_class = defaultdict(list)
for glyph in coverage.glyphs:
class_idx = class1_map.get(glyph, 0)
left_by_class[class_idx].append(glyph)
# Build right-side glyph lists per class
class2_map = getattr(class_def2, "classDefs", {}) if class_def2 else {}
right_by_class = defaultdict(list)
for glyph, class_idx in class2_map.items():
right_by_class[class_idx].append(glyph)
# Extract kerning values
for class1_idx, class1_record in enumerate(class1_records):
left_glyphs = left_by_class.get(class1_idx, [])
if not left_glyphs:
continue
for class2_idx, class2_record in enumerate(class1_record.Class2Record):
right_glyphs = right_by_class.get(class2_idx, [])
if not right_glyphs:
continue
kern_value = self._pair_value_to_kern(
class2_record.Value1,
class2_record.Value2
)
if not kern_value:
continue
for left in left_glyphs:
for right in right_glyphs:
pairs[(left, right)] += kern_value
return pairs
def extract_kern_pairs(self, font: TTFont) -> Dict[Tuple[str, str], int]:
"""
Extract all kerning pairs from GPOS PairPos lookups.
Args:
font: Font object to extract kerning from
Returns:
Dictionary mapping glyph pairs to kerning values
"""
pairs = defaultdict(int)
if "GPOS" in font:
gpos = font["GPOS"].table
lookup_list = getattr(gpos, "LookupList", None)
if lookup_list and lookup_list.Lookup:
for lookup in lookup_list.Lookup:
# Only process Pair Adjustment lookups (type 2)
if getattr(lookup, "LookupType", None) == 2:
for subtable in getattr(lookup, "SubTable", []):
fmt = getattr(subtable, "Format", None)
if fmt == 1:
format1_pairs = self._extract_format1_pairs(subtable)
for key, value in format1_pairs.items():
pairs[key] += value
elif fmt == 2:
format2_pairs = self._extract_format2_pairs(subtable)
for key, value in format2_pairs.items():
pairs[key] += value
return dict(pairs)
# ============================================================
# Legacy kern table methods
# ============================================================
@staticmethod
def add_legacy_kern(font: TTFont, kern_pairs: Dict[Tuple[str, str], int]) -> int:
"""
Create or replace a legacy 'kern' table with the supplied pairs.
Args:
font: Font object to modify
kern_pairs: Dictionary of kerning pairs
Returns:
Number of kern pairs written
"""
if not kern_pairs:
return 0
kern_table = newTable("kern")
kern_table.version = 0
kern_table.kernTables = []
subtable = KernTable_format_0()
subtable.version = 0
subtable.length = None # Recalculated by fontTools
subtable.coverage = 1 # Horizontal kerning, format 0
# Ensure proper types for kern table
subtable.kernTable = {
tuple(k): int(v)
for k, v in kern_pairs.items()
if v # Only include non-zero values
}
kern_table.kernTables.append(subtable)
font["kern"] = kern_table
return len(subtable.kernTable)
# ============================================================
# Name table methods
# ============================================================
def rename_font(self, font: TTFont, metadata: FontMetadata) -> None:
"""
Update the font's name-related metadata.
This method prefixes family, full, and unique names, and updates
the PostScript font name.
Args:
font: Font object to modify
metadata: The FontMetadata object containing the new names
"""
if "name" not in font:
logger.warning(" No 'name' table found; skipping all name changes")
return
name_table = font["name"]
# Update Name ID 1 (Family Name) and 16 (Typographic Family)
family_name_str = f"{self.prefix} {metadata.family_name}"
for record in name_table.names:
if record.nameID in {1, 16}:
try:
current_name = record.toUnicode()
if current_name != family_name_str:
record.string = family_name_str.encode(record.getEncoding())
logger.info(f" Name ID {record.nameID} updated: '{current_name}'->'{family_name_str}'")
else:
logger.info(f" Name ID {record.nameID} is already correct")
except Exception:
try:
record.string = family_name_str.encode("utf_16_be")
logger.info(f" Name ID {record.nameID} updated with UTF-16 BE encoding")
except Exception as e:
logger.warning(f" Failed to update name ID {record.nameID}: {e}")
# Update Name ID 4 (Full Name)
full_name_str = f"{self.prefix} {metadata.full_name}"
for record in name_table.names:
if record.nameID == 4:
try:
current_name = record.toUnicode()
if current_name != full_name_str:
record.string = full_name_str.encode(record.getEncoding())
logger.info(f" Name ID 4 updated: '{current_name}'->'{full_name_str}'")
else:
logger.info(" Name ID 4 is already correct")
except Exception:
try:
record.string = full_name_str.encode("utf_16_be")
logger.info(" Name ID 4 updated with UTF-16 BE encoding")
except Exception as e:
logger.warning(f" Failed to update name ID 4: {e}")
# --- Update Subfamily Name (nameID 2) and Preferred Subfamily (nameID 17) ---
for record in name_table.names:
if record.nameID in {2, 17}:
try:
current_name = record.toUnicode()
if current_name != metadata.style_name:
record.string = metadata.style_name.encode(record.getEncoding())
logger.info(f" Name ID {record.nameID} updated: '{current_name}'->'{metadata.style_name}'")
else:
logger.info(f" Name ID {record.nameID} is already correct")
except Exception:
try:
record.string = metadata.style_name.encode("utf_16_be")
logger.info(f" Name ID {record.nameID} updated with UTF-16 BE encoding")
except Exception as e:
logger.warning(f" Failed to update name ID {record.nameID}: {e}")
# --- Update Unique ID (nameID 3) ---
for record in name_table.names:
if record.nameID == 3: # Unique ID
try:
current_unique = record.toUnicode()
parts = current_unique.split("Version")
version_info = f"Version{parts[1]}" if len(parts) == 2 else "Version 1.000"
new_unique_id = f"{self.prefix} {metadata.family_name.strip()}:{version_info}"
if current_unique != new_unique_id:
record.string = new_unique_id.encode(record.getEncoding())
logger.info(f" Unique ID updated: '{current_unique}'->'{new_unique_id}'")
else:
logger.info(" Unique ID is already correct")
except Exception as e:
logger.warning(f" Failed to update Unique ID: {e}")
# --- Update PostScript Name (nameID 6) and other tables ---
new_ps_name = metadata.ps_name
name_updated = False
# 1. Try to update the name table (nameID 6)
for record in name_table.names:
if record.nameID == 6: # PostScript Name
try:
current_name = record.toUnicode()
if current_name != new_ps_name:
record.string = new_ps_name.encode(record.getEncoding())
logger.info(f" PostScript name table (nameID 6) updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript name table (nameID 6) is already correct")
name_updated = True
break
except Exception as e:
logger.warning(f" Failed to update PostScript name in name table: {e}")
if name_updated:
return
# 2. Fallback to CFF or post table if nameID 6 wasn't found or updated
if "CFF " in font:
top_dict = font["CFF "].cff.topDictIndex[0]
current_name = getattr(top_dict, "fontName", "")
if current_name != new_ps_name:
top_dict.fontName = new_ps_name
logger.info(f" PostScript CFF fontName updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript CFF fontName is already correct")
elif "post" in font:
post_table = font["post"]
current_name = getattr(post_table, "postscriptName", "")
if current_name != new_ps_name:
post_table.postscriptName = new_ps_name
logger.info(f" PostScript 'post' fontName updated: '{current_name}'->'{new_ps_name}'")
else:
logger.info(" PostScript 'post' fontName is already correct")
else:
logger.warning(" No PostScript name found in `name`, `CFF` or `post` tables.")
# ============================================================
# Weight metadata methods
# ============================================================
def update_weight_metadata(self, font: TTFont, filename: str) -> None:
"""
Update font weight metadata based on filename suffix.
Args:
font: Font object to modify
filename: Font filename to check suffix
"""
weight_map = {
"-Regular": ("Regular", 400),
"-Italic": ("Italic", 400),
"-Bold": ("Bold", 700),
"-BoldItalic": ("Bold Italic", 700),
}
base_filename = os.path.basename(filename)
# Find matching style and corresponding weight data
matched_style = None
for suffix, (ps_weight, os2_weight) in weight_map.items():
if suffix in base_filename:
matched_style = suffix
self._update_os2_weight(font, os2_weight)
self._update_postscript_weight(font, ps_weight)
break
if not matched_style:
logger.warning(
f" Filename doesn't match expected patterns {list(weight_map.keys())}. "
"Weight metadata skipped"
)
@staticmethod
def _update_os2_weight(font: TTFont, weight: int) -> None:
"""Update the OS/2 usWeightClass."""
if "OS/2" in font and hasattr(font["OS/2"], "usWeightClass"):
current_weight = font["OS/2"].usWeightClass
if current_weight != weight:
font["OS/2"].usWeightClass = weight
logger.info(f" OS/2 usWeightClass updated: {current_weight}->{weight}")
else:
logger.info(" OS/2 usWeightClass is already correct")
else:
logger.warning(" No OS/2 usWeightClass table found; skipping")
@staticmethod
def _update_postscript_weight(font: TTFont, weight: str) -> None:
"""Update the PostScript weight string."""
if "CFF " in font and hasattr(font["CFF "].cff.topDictIndex[0], "Weight"):
current_weight = getattr(font["CFF "].cff.topDictIndex[0], "Weight", "")
if current_weight != weight:
font["CFF "].cff.topDictIndex[0].Weight = weight
logger.info(f" PostScript CFF weight updated: '{current_weight}'->'{weight}'")
else:
logger.info(" PostScript CFF weight is already correct")
elif "post" in font and hasattr(font["post"], "Weight"):
current_weight = getattr(font["post"], "Weight", "")
if current_weight != weight:
font["post"].Weight = weight
logger.info(f" PostScript 'post' weight updated: '{current_weight}'->'{weight}'")
else:
logger.info(" PostScript 'post' weight is already correct")
else:
logger.warning(" No CFF or post table weight found; skipping")
# ============================================================
# PANOSE methods
# ============================================================
@staticmethod
def check_and_fix_panose(font: TTFont, filename: str) -> None:
"""
Check and adjust PANOSE values based on filename suffix.
Args:
font: Font object to modify
filename: Font filename to check suffix
"""
# PANOSE expected values for each style
style_specs = {
"-BoldItalic": {"weight": 8, "letterform": 3},
"-Bold": {"weight": 8, "letterform": 2},
"-Italic": {"weight": 5, "letterform": 3},
"-Regular": {"weight": 5, "letterform": 2},
}
if "OS/2" not in font:
logger.warning(" No OS/2 table found; skipping PANOSE check")
return
if not hasattr(font["OS/2"], "panose") or font["OS/2"].panose is None:
logger.warning(" No PANOSE information; skipping PANOSE check")
return
panose = font["OS/2"].panose
base_filename = os.path.basename(filename)
# Find matching style
matched_style = None
for style, specs in style_specs.items():
if style in base_filename:
matched_style = style
expected = specs
break
if not matched_style:
logger.warning(
f" Filename doesn't match expected patterns {list(style_specs.keys())}. "
"PANOSE check skipped"
)
return
# Check and fix values
changes = []
current_weight = getattr(panose, "bWeight", None)
current_letterform = getattr(panose, "bLetterForm", None)
if current_weight != expected["weight"]:
panose.bWeight = expected["weight"]
changes.append(f"bWeight {current_weight}->{expected['weight']}")
if current_letterform != expected["letterform"]:
panose.bLetterForm = expected["letterform"]
changes.append(f"bLetterForm {current_letterform}->{expected['letterform']}")
if changes:
logger.info(f" PANOSE corrected for {matched_style}: {', '.join(changes)}")
else:
logger.info(f" PANOSE check passed for {matched_style}")
# ============================================================
# Line adjustment methods
# ============================================================
def apply_line_adjustment(self, font_path: str) -> bool:
"""
Apply font-line baseline adjustment to the font.
Args:
font_path: Path to the font file
Returns:
True if successful, False otherwise
"""
try:
# Check if font-line is available
result = subprocess.run(
["which", "font-line"],
capture_output=True,
text=True
)
if result.returncode != 0:
logger.error(" font-line utility not found. Please install it first")
logger.error(" See: https://github.com/source-foundry/font-line")
return False
# Apply font-line adjustment
subprocess.run(
["font-line", "percent", str(self.line_percent), font_path],
check=True,
stdout=subprocess.DEVNULL,
stderr=subprocess.PIPE
)
# Handle the renamed output file
base, ext = os.path.splitext(font_path)
linegap_file = f"{base}-linegap{self.line_percent}{ext}"
if os.path.exists(linegap_file):
os.remove(font_path)
os.rename(linegap_file, font_path)
logger.info(f" Line spacing adjusted ({self.line_percent}% baseline shift)")
return True
else:
logger.warning(f" Expected font-line output '{linegap_file}' not found")
return False
except subprocess.CalledProcessError as e:
logger.warning(f" font-line failed: {e}")
return False
except Exception as e:
logger.warning(f" Unexpected error during line adjustment: {e}")
return False
# ============================================================
# Main processing method
# ============================================================
def process_font(self, kern: bool, remove_gpos: bool, font_path: str, new_name: Optional[str] = None) -> bool:
"""
Process a single font file.
Args:
font_path: Path to the font file
new_name: Optional new family name
Returns:
True if successful, False otherwise
"""
logger.info(f"\nProcessing: {font_path}")
# Load font
try:
font = TTFont(font_path)
except Exception as e:
logger.error(f" Failed to open font: {e}")
return False
# Generate metadata
metadata = self._get_font_metadata(font, font_path, new_name)
if not metadata:
return False
# Process font
try:
# Update names
self.rename_font(font, metadata)
# Fix PANOSE and weight metadata
self.check_and_fix_panose(font, font_path)
self.update_weight_metadata(font, font_path)
if kern:
# Handle kerning
kern_pairs = self.extract_kern_pairs(font)
if kern_pairs:
written = self.add_legacy_kern(font, kern_pairs)
logger.info(
f" Kerning: extracted {len(kern_pairs)} pairs; "
f"wrote {written} to legacy 'kern' table"
)
else:
logger.info(" Kerning: no GPOS kerning found")
else:
# Skip kerning step
logger.info(" Skipping `kern` step")
# Remove GPOS if requested and kerning was processed
if remove_gpos and kern and "GPOS" in font:
del font["GPOS"]
logger.info(" Removed GPOS table from the font.")
# Generate output filename
output_path = self._generate_output_path(font_path, metadata)
# Save modified font
font.save(output_path)
logger.info(f" Saved: {output_path}")
if self.line_percent != 0:
# Apply line adjustments
self.apply_line_adjustment(output_path)
else:
logger.info(" Skipping line adjustment step")
return True
except Exception as e:
logger.error(f" Processing failed: {e}")
return False
def _generate_output_path(self, original_path: str, metadata: FontMetadata) -> str:
"""Generate the output path for the processed font."""
dirname = os.path.dirname(original_path)
original_name, ext = os.path.splitext(os.path.basename(original_path))
# Detect style suffix
suffix = ""
for valid_suffix in VALID_SUFFIXES:
if original_name.endswith(valid_suffix):
suffix = valid_suffix
break
# Build new filename
base_name = f"{self.prefix}_{metadata.family_name.replace(' ', '_')}{suffix}"
return os.path.join(dirname, f"{base_name}{ext.lower()}")
def validate_font_files(font_paths: List[str]) -> Tuple[List[str], List[str]]:
"""
Validate font files for processing.
Args:
font_paths: List of font file paths
Returns:
Tuple of (valid_files, invalid_files)
"""
valid_files = []
invalid_files = []
for path in font_paths:
if not os.path.isfile(path):
logger.warning(f"File not found: {path}")
continue
if not path.lower().endswith(SUPPORTED_EXTENSIONS):
logger.warning(f"Unsupported file type: {path}")
continue
# Check for valid suffix
basename = os.path.basename(path)
has_valid_suffix = any(
suffix in basename for suffix in VALID_SUFFIXES
)
if has_valid_suffix:
valid_files.append(path)
else:
invalid_files.append(basename)
return valid_files, invalid_files
def main():
"""Main entry point."""
parser = argparse.ArgumentParser(
description="Process fonts for Kobo e-readers: add prefix, kern table, "
"PANOSE validation, and line adjustments.",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog="""
Examples:
%(prog)s --name="Fonty" --line-percent 20 *.ttf
%(prog)s --prefix NV --name="Fonty" --line-percent 20 --skip-kobo-kern *.ttf
"""
)
parser.add_argument(
"fonts",
nargs="+",
help="Font files to process (*.ttf)"
)
parser.add_argument(
"--name",
type=str,
help="Optional new family name for all fonts"
)
parser.add_argument(
"--prefix",
type=str,
default=DEFAULT_PREFIX,
help=f"Prefix to add to font names (default: {DEFAULT_PREFIX})"
)
parser.add_argument(
"--line-percent",
type=int,
default=DEFAULT_LINE_PERCENT,
help=f"Line spacing adjustment percentage (default: {DEFAULT_LINE_PERCENT})"
)
parser.add_argument(
"--skip-kobo-kern",
action="store_true",
help="Skip the creation of the legacy 'kern' table from GPOS data."
)
parser.add_argument(
"--remove-gpos",
action="store_true",
help="Remove the GPOS table after converting kerning to a 'kern' table."
)
parser.add_argument(
"--verbose",
action="store_true",
help="Enable verbose output"
)
args = parser.parse_args()
# Configure logging level
if args.verbose:
logging.getLogger().setLevel(logging.DEBUG)
# Validate files
valid_files, invalid_files = validate_font_files(args.fonts)
if invalid_files:
logger.error("\nERROR: The following fonts have invalid filenames:")
logger.error("(Must end with -Regular, -Bold, -Italic, or -BoldItalic)")
for filename in invalid_files:
logger.error(f" {filename}")
if not valid_files:
sys.exit(1)
response = input("\nContinue with valid files only? [y/N]: ")
if response.lower() != 'y':
sys.exit(1)
if not valid_files:
logger.error("No valid font files to process")
sys.exit(1)
# Process fonts
processor = FontProcessor(
prefix=args.prefix,
line_percent=args.line_percent,
)
success_count = 0
for font_path in valid_files:
if processor.process_font(
not args.skip_kobo_kern,
args.remove_gpos,
font_path,
args.name,
):
success_count += 1
# Summary
logger.info(f"\n{'='*50}")
logger.info(f"Processed {success_count}/{len(valid_files)} fonts successfully")
if success_count < len(valid_files):
sys.exit(1)
if __name__ == "__main__":
main()